It depends on what you want. Do you want to maximize stats, gold making, or a bit of each? Gathering professions are exceptionally nice on a Druid since being mounted is less of a concern, and thus make you more efficient at gathering and thus making gold via those professions. Whereas for stats, it depends on if you're a DPS (procs or on-use effects can be good @engi/tailor), a Healer (static stats are usually best) or a tank (armor enchant and rocket boosts for extra mobility @engi). Skinning & Leatherworking can be decent money-makers, and can help you gear up your character if it's still in need of that sort of thing.